Reading the Atmosphere

Scientists track the greenhouse effect with precise measurements taken at stations worldwide. The Mauna Loa Observatory has recorded CO2 continuously since 1958, creating the Keeling Curve that has climbed from 315 ppm to over 420 ppm.

Before instruments existed, ice cores from Antarctica preserved ancient air bubbles revealing CO2 levels across 800,000 years. Across all that time, CO2 never exceeded 300 parts per million — today's level is unprecedented in the geological record.

Satellite measurements confirm that Earth is trapping more energy than it releases into space. This energy imbalance is the greenhouse effect made visible from orbit.